Work handling mechanism for furnaces



m vbu ATTORNEY .-J INVENTOR fiarold .[Mss

4 Sheets-Sheet 1 H J- NESS WORK HANDLING MECHANISM FOR FURNACES Sept. 5, 1950 Flled July 17, 1943 Sept. 5, 1950 H. J. NESS WORK HANDLING MECHANISM FOR FURNACES 4 Sheets-Sheet 2 Filed July 17, 1943 INVENTOR flarald J/Vss 57M 4 M ATTORNEY Sept. 5, 1950 H. J. Mass WORK HANDLING MECHANISM FOR FURNACES 4 Sheets-Sheet 3 Filed July 17 1943 INVENTOR ll aroldfji/Ess mmwwua ATTORN EY Sept. 5, 1950 Filed July 17, 1943 H. J. NESS WORK HANDLING MECHANISM FOR FURNACES 4 Sheets-Sheet 4 INVENTOR [lara Z0 Jf lV ess 217 ham ATTORNEY Patented Sept. 5, 1950 j umreo STATES rm- OFFICE I Wonk HANDLING MEoHAmsM Fon '7 V FURNACES Harold J; Ness, Montclair,N."J., assignor to Metallurgical Processes 00.,' Newark, N. .L, a

partnership Application July 1 7, 1943; Serial No. 495,113

" 14 Claims. (01. 214-18) This invention relates to metallurgical fur- I naces of the controlled atmosphere type and more particularly to conveying and quenching mechanism for the parts to be heated therein. This application contains certain subject matt er originally described in my applications Serial v lNos. 384.641 and 455,720, filed March 22; 1941, appear.

and August 20, 1942, respectively, now Patents Nos. 2,346,698 and 2,394,002. p

' Briefly, the aforesaid applications relate to the production of a lithiated furnace atmosphere 2 Another object is to provide a novel conveyor mechanism for 'ahe'at treating furnace which is simple, sturdy and convenient to operate.

"Another object is to provide a novel quench chute and supporting means therefor.

Other objects and advantages will hereinafter The quenching mechanism comprises a chute extending directly from the heating chamber of the'furnace into'a tank containing the quenching medium. The conveyor comprises a flexible in which the atmosphere may be composed of gases resulting from the reaction of a hydrocarbon fuel and air at a relatively high temperature to which is added the vapor of a compound or compounds of lithium.

from moisture and is non-oxidizing to metals heated therein. It may be either carburizing or non-carburizing, depending upon the pro- Such an atmosphere, when properly produced, is substantially free portion of carbon monoxide andmethane therein. The parts treated in such a lithiumatmosphere become coatedwith a thin protective layer of lithium compounds, so that, if desired, they may be removed from the furnace and cooled in air without oxidation, or they may be quenched directly from the furnace atmosphere.

The present invention is concerned with conveying and quenching mechanism for such a furnace in which the conveyor may be moved to or through the door opening of the furnace for loading, then into the furnace for heating of the parts and, after the treatment is completed,

moved either to or through the door for removal of the parts or moved into position to discharge the parts directly from the atmosphere into a quenching medium without necessitating the opening of the furnace door.

One of the objects of the present invention is to permit all or a part of the work parts to be discharged directly from the furnace atmosphere into a quenching medium without passing through or in contact with the air.

Another object is to providea conveyor mechanism which may be moved into position to discharge the work parts into the quenching medium without opening of the heating chamber to the air.

Another object is to provide means for directing the conveyor into position to discharge the work parts either into the quenching medium or in position to permit loading or unloading thereof through the furnace door.

Another object is to control the path of movement of the conveyor in accordance with the open or closed position of the door.

or jointed bed of a length corresponding approximately to that of the heating chamber and" the throat of the quench chute is provided with movable bridging means whereby to direct the conveyor' either across the throat for movement to or through the furnace door or to permit it to move into'the' quench chute for discharge of its load therein. Thebridging member maybe controlled in relation'to" the open or closed position of the door so that forward movement of the conveyor, "withthe door closed, will cause discharge of" the work parts into the quench chute whereas forwardmovement of the conveyor when the door is open will cause the conveyor to move to or through the door opening. v

The invention will'be more fullyunderstood by reference to the accompanying drawings where in: r

Fig. 1 is a'vertical sectional view of an atmosphere furnace embodying the present invention; Fig. 2 is a fragmentary perspective view of the muffle of such a furnace illustrating the-conveyor mechanism and quench chute;

Fig. 3 is a'sectional view on-the line 3-'-3-of Fig. 4 is a view similar to Fig. 2 showing a modified form of conveyor and quench chute;

Fig. 5is afrag-mentaryview of the conveyor guiding means for the quench chute shown in Fig.4; Fig. 6 is a-fragmentary view of one form ora flexible conveyor; 7

Fig. '7 15a fragmentary view of a different form of fiexibleconveyory-and Fig. 8 is a vertical sectional view of a modified furnace provided with a quenching chute d a cooling-chamber.- I 1 bustion chamber l2, and the rear of the muliie terminates within an opening i3 in the rear wall of the chamber l2. The forward end of the muftie is provided with a flange M to which is secured a muliie extension l5 provided with a suitable door i6 at its outer end. The door may be controlled by a foot pedal I! connected thereto through a flexible cable l8 passing over suitable pulleys I51 and 21. The pedal I7 is pivoted at 2'2 and is adapted to be held in suitable raised position by means of a latch 23 thereon engaging in suitable notches in the serrated plate 24. Extending downwardly from the :mu'iii e extension I5 is a quenching chute 25 which terminates beneath the body of quenching medium 26 contained within a suitable receptacle 2?.

The muiile It is heated by two series of burners 28 extending into the combustion chamber l2 at opposite sides thereof beneath, the muflle Ii]. '1'he burners 28 are supplied with aconib'ust'ible mixture of air and gas froma manifold 29. The combustion chamber 12 is vented by 'a plurality of pipes extending from a point above the center of the mufile 10, through the refractory insulation, and terminating above the furnace shell. Situated to the rear'of "the combustion chamber I2 is a vaporizing unit 3| and ages generating unit 32. The vaporizing unit 3| includes a combustion chamber '33 provided with burners S4 supplied with a combustible mixture of gas and air from a manifoldf35, and is vented by ports 36. The air and gaslin'es G'Ifa'nd 38 are each provided with two branches, "the branch air lines having electrically controlled valves 39 and 41 therein, by which air iindersiiit'able pressure is supplied to a pair of Venturi mixing tubes 42 and 43, respectively, connected to themariifolds f2}? and associated with the burners 2 8 and 34, respectively. The two branches of the gas line 38 are provided with pressure regulating vanes 44 and 45, the outlet "sides o'f whichJa're connected to the throats of the Venturi tubes '42'and'43, respectively. The valvesf3'9'and 4| are operated under the control of thermocouples located in the combustion chambers l2 and '33, respectively.

The gas generating unit 32 ;comprises asubstantially rectangular combustion chamber 46 provided with suitable burners'lfl, vents 48 and 'a cracking chamber 49. Thecracking chamber is a substantially U-shaped chamber "of a heat resisting metal or alloy andis ,provided'w-ith inlet and outlet conduits 50 and 5| connected into the free ends of the opposite arms ofthe cracking chamber. The inlet conduit 50 is connected-to a suitable source of gas and air, such as described in my aforesaid application Serial No. 455,720, and comprising, briefly, a plurality of gas control valves 52a--c and associated air control valves 53ac, whereby different ratios of gas and air may be readily obtained The gaseous mixture is forced, by a'pump 54, u der a slight pressure into the cracking chamber 4,9, The-gas and air mixture is heated in the chamber to the cracking temperature, fromabout 1400" F. to "1900" F., to effect a reaction between the gases after which they are conducted by the outlet conduit 5| into a condenser 55 wherein they are cooled to approximatelyroom temperature, to

,remove a portion of the water vapor therefrom. The partially dried reaction products are then :conducted by a conduit 56 into a lithium compound vaporizing chamberj'l suspended in the combustion chamber 33. The chamber 51 has an open top, closed by a close fitting cover 58, through which a cartridge 59, containing lithium compounds, may be introduced into the chamber. A partition plate 6| depending from the cover 58 causes the, incoming gases to be deflected over the cartridge 59 so as to entrain the vapors therefrom and to carry the same through the conduit 62, into the mufile I0.

The lithiated reaction products may be either neutral or 'carburizing depending upon the ratio of gas and air admitted into the cracking chamher. In either case, the presence of lithium renders the gas substantially dry and nonoxidizing to the work parts introduced into the muiile. The work parts after treatment may be removed from the mufiie and air cooled, or they maybe quenched directly from the protective atmosphere. The present invention is concerned with the conveying and quenching mechanism by which the parts *may be carried into and out of the furnace for either air cooling or for quenching. This mechanism will now be described by reference to Figs. 1 andZ. 4 v

Located on the floor of the mu'file it *and adapted to slide thereon is a conveyor '63 composed of aseries of hat'plates'fifl having a portion at each side bent upwardly to form a flange F5. The successive units are coupledtogether by links 66 loosely pivoted to the oute'r'sides or the adjacent ends of the flanges 165. The individual plates may be of any *c'onvenient length, except they must/not be longer than the depth of the throat of the quench chute 25, since it is necessary that they pass into'th'e quench chute under conditions as will hereinafter appear. The rear plate '84 has a drawb'ar 6! pivotany secured thereto and extending forw'arc'lly through the muffle and through a suitableslot 6:8 in the door it, thus permitting the conveyor to be moved forwardly or backwardl y in the muffle. The connection of the drawbar 61 to the rear of the conveyor leavesth'e forward end thereof free to pass into the "quench chute as the conveyor -is drawn forward, as will hereinafter appear.

The quenching chute '25 adjacentits upper end I is provided at the rear thereof with an angular extension 69, bridged by a 'solid'concave plate "H a-nizl'having three'convex rails T2 extending thereacross. Pivoted at the 'juncture'of the upper-end of the chute 725 and the forward end of the m'uiii'e extension [5 is a br'i d'gingmeinber 73 which normally extends downwardly against the forward wall of the chute "25, as shown in dotted lines. This member is secured tofa shaft T4 extending externally of the chute where it is provided with an operating arm 15 pivoted to the upperend of a plunge rod '16 having ap-iston Ti working within a. cylinder .18 mounted on a pit/ch19. The plunger is adapted to bepperated pneumatically to move the bridgingmember 73 from the position shown in'dotted lines in Fig. 1 to the horizontal position shown infull lines soas to bridge the upper end of the 'chute 2'5. The bridging member comprises two arms which extend between the rails '12. It is'c'ontrclle'd b means of suitable electric valves 8! and operated by means of the foot pedal l'ithrough theinercury switches 33 and 84. The cylinder '58, at its upper endabove the piston TI, is connected bya flexible c'onduitiifi to a source of low pressure air,'and at its lower end, beneath the piston, it is connected by a fiexibleconduit '86 to the'valVe'B? by which it may be'supplied 'w'ith'high pressur air. The valve 8| 'provides'a vent'fro'm the conduit 36 to the outer air. With the door I6 closed, the

mercury switch 84is open and the winding of the valve 82 is deenergized while the mercury switch 83 is closed and the winding of valve 8| is energized to maintain the former closed and the latter open, connecting the conduit 86 to the atmosphere and permitting the low pressure air to maintain the plunger depressed and the bridge member 13 in its downward position clear of the throat of the chute 25. However, when the foot treadle is depressed, to open the door I6, the switch 83 opens, deenergizing the valve 8| to close the same, and the switch 84 is closed to energize and open the valve 82, thus permitting the high pressure air to enter beneath the piston 11 to raise the same against the opposing force of the low pressure air, thereby to move the bridge member 13 to its upward or horizontal position so as to bridge the throat of the chute 25. In this position of the member 13, the conveyor eie ments 64 may be withdrawn to the forward end of the furnace adjacent the door for loading. After they have been loaded and positioned within the muffle Hi, the door I6 may be closed b the upward movement of th pedal ll. The switches 84 and 83 reverse the positions of the valves BI and 82 so as to exhaust the lower portion of the cylinder 18 and permit the low pressure air supplied to the upper portion thereof through the conduit 85 to return the bridging member 13' to its vertical position adjacent the front wall of the chute 25. When the carburizing or heat treating operation has been completed, the drawbar B! is drawn forward, with the door it closed, thus pulling the conveyor elements to the throat Of the chute 25 down which they then travel by gravity, permitting the treated parts thereon to be dumped one after the other through the chute 25 and into the quenching bath 26. The conveyor may be advanced to the throat of the quench chute at such rate, depending on the nature of the load and the rate of circulation of the quenching medium in the quench tank, as to keep the parts suificiently separated to enable the oil to absorb the heat therefrom without local overheating at the base of the chute, whereby an even quench and uniform hardness is obtained. The atmosphere for the muffle I is exhausted through the vent 81 which extends from a point adjacent the lower end of the quenching chute 25 upwardly to above the level of the muflle and as it escapes into the open air, it is ignited by means of a pilot burner 88 having a conduit 88 connected to the gas line 38.

At times in the treatment of certain steels it may be necessary to cool the treated parts to near or below the lower limit of the critical temperature before quenching, and for this purpose it is convenient to draw the conveyor with its work parts into the muffle extension for such precooling in the lithiated atmosphere. In such cases it is necessary to -maintain the bridging member 13 in its bridging position while the door l6 remains closed. For this purpose I have provided a manual switch 90 of the double pole type, in circuit with the windings of the control valves 8! and 82. Normally this switch is in the upper position shown in Fig. l, but when it is desired to raise the bridging member 13 independently of the closed position of the door, the switch is moved to its lower position, thereby interrupting the circuit to the vent valve 8! to close the same and applying current to the high pressure air valve 82 to open the same, thereb to raise the bridging member. The conveyor may then be moved to the forward end of the muffle for precooling, after which it may be again moved backward into the muffle, the switch 98 raised to effect a lowering of the bridging member and theconveyor. again drawn forward to deposit its charge into the quench chute.

' It will be noted, therefore, that after the parts have been loaded in the furnace and the door closed, they are continuously subjected to the atmosphere introduced through the conduit 62 into the muffle in until they enter the quenching bath.

, The circulation of the lithiated gases in the chute also causes a portion of the lithium or its compounds to be taken up by the oil which is continuously circulating in the base of the quench chute and to be mixed therewith. Due to the sudden condensation of the vapor of lithium or of the carbonate or oxide thereof, upon contact with or entrainment by the cool oil, this material solidifies in an extremely fine state of subdivision and in this state these alkali salts are particularly effective saponifying agents for lard oils or other fatty oils which I provide in the oil, thus producing soaps or metallic esters of the fatty acid which greatly increase the wetting properties of the oil. These metallic esters are formed primarily in the base of the quench chute where the work first comes in contact with the 011. As a combined result of the oil circulation in the quench chute and the increased wetting property of the oil, there is a complete absence of frothing in or adjacent the base of the quench chute and better and more even quenching of the work parts results.

In addition to this increased interfacial tension of the quenching oil with the work parts, the absorption of lithium carbonate into the oil neutralizes the free acid in the oil and thereby prolongs the useful life thereof. In the absence of this absorbed lithium and lithium compounds, the fatty acid content of the oil oxidizes and becomes rancid. As the acid content thus builds up the physical characteristics of the oil are modified and its quenching properties altered. In addition the fatty acids solidify and accumulate in the oil and upon contact with the work parts prevent proper contact of local areas thereof with the quenching medium.

The quench chute 25, as stated, is secured to the forward end of the muffle and is supported in part thereby. To provide additional support while permitting the forward expansion of the mufile, a bracket 9| (Figs. 1, 2 and 3) is mounted on the forward wall of the furnace. Carried by the bracket 9| is a transverse plate 92 having two bolts 93 threaded therein and locked in place by nuts 94. The heads 95 of the bolts 93 are machined flat and adjusted into engagement with the underside of the angular extension 69 of the chute 25. The mufile I0 is anchored at its after end by a pin 96 and, as it is brought up to heat, it expands forwardly, causing the quench chute to slide outwardly on the heads of the bolts 83. The overhanging ends of the plate 92 provide sufficient rigidity to give the required support to the chute 25, but are also sufficiently resilient to prevent binding of the muffle in the front wall of the furnace.

The conveyor arrangement shown in Figs. 1 and 2 is suitable for small furnaces in which the length of the conveyor is less than the height of the quench chute above the level of the quenching medium 26. It is not desirable, however, to have the conveyor elements enter the quenching medium since the frequent heating and quench- 'ingthereof tends to deteriorate and .dirty the same.-

In Fig. 4'Ihave shown amodified'formr'oflcone veyor and quench chute adapted for :longer' muflies. In this modification .the workconve'ying belt :IGI "is in the form of 1 a woven or' mesh belt having a series of upstanding ipivoted li-nks I 02 along the sides 'thereof to form a trough. The links 102 have offset overlapping pivoted ends, as-more clearly shown in Fig. 6. Lateral tabs I03 bent out from the body of the links form anchorages for the strands -of :the mesh portin 'mtof the conveyor. Theconveyorristfree at its forward end-and is secured to adrawba'r illiat itsrear end, similar to the drawbar ifl ofsFigs. 1 and 2, whereby the con-veyormay be moved to and fioalong the floor of the mufiie. 'lhe -quench chute 4'90 is provided with the same :throat or bridging member :I 3 described in connection with Figs. v1 and2, acrosswhich the conveyormay be drawn to or throughthe-door openingof the muIrle-toenable the conveyorto beilo'aded avith the parts to be treated. After Heading of the conveyor it is-movedto the rear ofathemufile by the drawbar I I15 and thedoor I6 closed. The closing of the door lowers the bridging member against the front face of the chute Midas show-n.

treatment of the parts has been completed they-may either beremoved from the furnace and cooled in the -air or quenched, as desired If -:they :are to be ai: cooled, the'door is aga'in opened, which, as described, causes the bridging member 13 to vbe -raisezf whereby the conveyor-may he .dra-wnforwardly =to-or through the door opening. "If they-are to vbe quenc'hcd, however, the .door remains closed so that the bridging member remains lowered as the bar :I Ii-S is drawn forward During'this movement, .the forward .end of the conveyor drops lby its own weight into the .chute I 86, engaging between theacurved rails IIl'I .and a pair of spaced -guide fingers I108 whereby the conveyor .is directed intosareceptacle 3B9 formed-to therear of the quench :chute. .The curvature of the rails IT and 'the guides .1138 is such :that the conveyor overhangsithetrear wall nix-the chute MIG so that the work parts as they fall :from the conveyor 'pass'vfreely .through the chute into the quenching Qm'edium. During the forward .-movem-ent of :the conveyor it accumulates inJ-I-the chamber {Hi9 and .isthus protected from engagement with the tquenching medium and thus :theudeteriorating effect of frequent quenching is avoided. IEheshelt also remains clean .and the .quenchingmediumis not carried into the pmufiieon the conveyor, as would be thecase if the conveyor was pcrmittedt-o enter th -qu nch tank.

.In {the case .ofshort conveyors, for use .in. small "furnaces, the :front section ;of theconveyor may be:brought tothedoorsofthe muffle and the com iueyor loaded or unloaded, as by means .of tongs or other :Work handling means, through the open door of :the:mufile. :However, :in th lease nfdong conveyors, this method {of loading and unloading ,of the conveyor is cumbersome and, therefor, -I provi a conveyor suppor adjacen the door upon which the conveyorginay be'position'ed for-loading and unloading. This sup- :porting-zmeans may oomprisea pair of rails III, secured to "a shaft 5H2, pivoted beneath the .muiile extension =on any-suitableubracket H3, in fiilohiaway thatthe nail :assembly normally reets a ainst thefiont ,wall 5H4 of the quench chute cov r, :as indicated in dotted :lines Fist-.4, but

are movable to the full line position to form '3 continuation of the muffle floor, upon which the conveyor maybe drawn for loading or unload: ing. A folding strut H5 is pivoted at its lower end on a trunnion H6 carried by the wall I and at its upper end to the inner side of the rail members II. This strut comprises an up per pair of arms II'I hinged at H8 to the outer sides of a lower arm H9 in such manner that when the rails are lowered against the wall II'Q'. the strut folds against this wall With-the arms H9 and H1, and the rails III, in nested rclation. Lateral extensions I20 on the lower arm I I9 prevent movement of the hinge beyond the aligned position of the arms, as shown, and thus impart rigidity to the strut.

In Fig. 7 I have shown a modified form ,of conveyor in which the upstanding edge I 2| :is woven as an integral part of the body portion I22 of theconveyor. The drawbar I23 is secured to a plate I24 welded to the flange portion 12! at its rear ed e. It has been found that such a structure is sufiiciently flexible to readilyenter the quench chute I86 and the storage chamber I09. The flanged edges I2I, however, inrpart sufficient rigidity to the conveyor so that it may be moved to and fro along the mufile floor smoothly and without buckling.

It will be understood, of course, that in place of the woven mesh structure, a link or other form of flexible belt may be employed. The conveyor is preferably composed of a heat resisting metal such as nickel or nickel-chromium alloy, but this is not essential since the good life is obtainable with conveyors composed of steel since they are continuously under the protection of the lithium atmosphere while in the muflie I0 and the storage chamber I08, and are protected by the coating of lithium compounds when with,- drawn to or through the door opening'for-loada ing and unloading, In order to prevent stagnation of the lithiated atmosphere-in the'cham; ber I09, it is connected to the quench chute vent pipe 87 by a conduit I25 (Fig. 4) so as .to permit gas circulation therethrough.

In Fig. 4 I have shown a modified form of support for the mufile extension and quench chute I56, comprising a pair of brackets I26 each composed of a horizontally disposedangle I21, a vertical angle I28 and an intermediate gusset-plate I29.

The brackets are secured to the front wall I3l of the furnace, adjacentcach side of the quench chute, as by boltingoraweld ing, and the horizontal angles support a pair of roller brackets I32. The quench chute I06 has secured to each side thereof an angle I33 positioned so as to rest upon the rollers I34 whereby the muffle is supported in a manner to permit it to move fore and aft'as the muffle expands and contracts.

While it is ordinarily preferable to employoa conveyor-in connection with the quench chute, it is to be understood that this is not essential, and in Fig. 8 I'have shown a quench chute and associated bridging member adapted for use when no conveyor is employed. In this arrangement it is contemplated that the parts willbe pushed through the muilie in a continuous succession and either be quenchedas they leave the rear of the muflie or pass over the bridging member into a cooling chamber, where they maybe coolediin the lithiated atmosphere. In Fig. .8 the muille is formed in two sections I35 and I3! secured to the intermediate quench chute I38. Thefront muffle J36 serves as the-heating chamber and is heated by a combustion chamber I39 having Suitable burners MI and vents I42. It is closed by a door I43 and is vented by a conduit I44 at its forward end. The rear muffle I31 serves as a cooling chamber and may be provided with a jacket I45 whereby a suitiable cooling fluid may be circulated therearound. It has a vent I46 and is normally closed by a sliding plate or partition I41.

The lithiated atmosphere is shown entering at the center of the mufile assembly and passing, by means of a T-coupling I48, into the conduits I49 and II extending respectively along the roof of the front and rear muffle sections I36 and I31. The conduits I49 and I5I are slotted, as at I52, to permit entrance of the atmosphere into each of the muflle sections at spaced points therealong.

The quench chute I38 extends downwardly between the front and rear muffle sections into a quench tank I53 and is vented by a conduit I54 extending upwardly from the quench chute just above the level of the quenching medium. The throat or bridging member I55 is in the form of a solid plate secured to a pivoted shaft I56 operated by an air cylinder I51 in the same manner as shown in Fig. 1, except that it is controlled by means of a manual switch I58.

A heat baffle I59 in the form of a flexible chain or woven mesh curtain depends from the roof of the muflle and tends to isolate the cooling chamber from the heating chamber. A vestibule I6I in the form of an extension of the rear mufile I31 is provided with a door I62, which is normally closed when the slide I41 and the front door I43 are open, during the loading operation, so as to prevent an influx of air into the-mufiles. The door I43 and slide I41 are adapted to be operated either in unison or the front door I43 may be operated separately, depending upon whether the bridging member I55 is in bridging position or in its lowered position. The door I43 and the slide I41 are, respectively, operated by cables I83 and I64 passing over pulleys I55 and I66 and attached to the plungers of air cylinders I61 and I68. The air cylinders are supplied, above their respective plungers, with high pressure air by conduits I69 and HI under control of a valve I12, and may be vented to the outer air by a valve I13. Low pressure air is continuously applied to the cylinders beneath the plungers by a conduit I14. The valves I12 and I13 are operated electrically under control or a push button type toggle switch I15, shown diagrammatically. With the lower button C depressed, switch contacts I16 are open, effecting closure of the Valve I12 in the high pressure air line, and contacts I11 are closed to operate the valve I13 so as to vent the upper side of the plungers in the respective air cylinders to the outer air. The plungers are therefore raised by the low pressure air, permitting the doors to lower to their closed position. Depression of the upper button 0 operates the high pressure air valve I12 to open position and permits the vent valve I13 to close, whereupon the high pressure air above the plungers force the same downwardly, raising the door I43 and the slide I46.

The high pressure air line branch I1I for the rear cylinder I68 has a. supplemental valve I18 therein which operates in parallel with the high pressure valve I16 of the bridge controlling cylinder I51 so that valve I18 is open only when the bridging member is in its raised position. With the manual switch I58 on its left contact to effect a lowering of the bridging member, the

10 valve I18 is retained closed and operation of the button 0 of switch I16 effects opening only of the entrance door I43.

The vestibule door I62 is operated by a cable IBI passing over pulley I32 and attached to the plunger I83 of an air cylinder I64. The high pressure air valve I85 and the vent valve I86 associated with the cylinder I84 are controlled bya manual switch I81. Contacts I88 of switch I81 are normally closed and are connected in circuit with the vent valve I86 so as to maintain this valve open so that the plunger in the cylinder is normally raised and the door I62 is closed. Contacts I89 of switch I81 are normally open and are connected in circuit with the high pressure valve I85 and contacts I11 of switch I15 so that valve I85 is normally closed. When it is desired to' open the door I62, the switch I81 is operated to' open the contacts I88 and to close contacts I89,

thereby closing the vent valve I85 and opening the high pressure air valve I85. This latter valve is opened, however, only in case the switch I15 is in its closed position, that is, only when the front door I43 and the vestibule slide I41 are closed.

The lower wall or floor of the vestibule .I6I slants downwardly and is provided with a series of anti-friction rollers I9I so that upon opening of the door I62 any work parts which may be in the vestibule will be discharged therefrom- A suitable conveyor or Work receiving table, not shown, may be disposed adjacent the door I62 to receive the parts discharged from the vestibule.

In the operation of this furnace the parts to be treated are introduced through the door I43 at intermittent periods, each work part serving to advance the entire line through the muflle as sembly. If precooling is desired, the bridge member I55 is elevated by moving the switch I58 to its :right hand position. The parts are thenpushed across the member I55 and through the cooling chamber I31, When the entrance door I43 is opened to insert a cold part, the slide I41 is simultaneously opened to permit a cooled part to be removed from the cooling chamber into the vestibule I6I. However, if the parts are to be quenched, the switch I 58 is placed on its left contact, lowering the bridge member I55 and closing the valve I18 so as to retain the slide I41 closed. Each new work part introduced into the heating chamber will thus push a heated part into the quench chute, through which it falls into the quenching medium in the tank I53.

It will be understood, of course, that other arrangements and constructions of the quench chute, its bridging member and the conveyor mechanism may be devised and I, therefore, do not desire to be limited to the exact constructions and arrangements shown, but contemplate all forms thereof coming within the scope of the appended claims.

What I claim is:

1-. In a furnace, the combination of a chamber havinga heating section and a loading section, a door normally closing said chamber adjacent to said loading section, means for operating said door to an open position, a flexible conveyor having oppositely disposed ends, said conveyor providing a continuous work holding surface movable to and, fro in said chamber between said loading and heating sections, and means extending through said door and secured to one end only of said conveyor for actuating said cone H veyor in either directioninsaid chamber in either the closed or open position of said door.

2. In a furnace, the combination of a chamber having a heating section and adischarge section, a door normally closing said chamber, an articulated conveyor having oppositely disposed ends and providing a continuouswork holding surface movable to andfroin said chamber between said heating-section and said dischargesection, a single means for actuating said conveyor in eitherdirection" in said chamber, a discharge opening in the base of the discharge section. of said chamber, and means for directing one end, of said. conveyor into said discharge opening.

3-..In a furnace, the combination of a heat treating chamber having a. heating section and a discharge section, adoor normally closing said chamber, a fiexibleconveyor providing acontinuous work holding surface movable. to and fro insaid chamber between. said heating section and saiddischargesection,means for actuating said conveyor in either direction in said chamber, adischargeopening.inthebase of the discharge section of said chamber, and selectively operable. means for directing said conveyor, in one directionof movement thereof; either into or across said. discharge opening.

4; In afurnace, thecombination of a chamher having a heating section, and a discharge section, a, door normally closing said chamber, a work holding conveyor-having oppositely disposed'ends. said conveyor being movable to and fro in said chamber between said heating section and said discharge section; a discharge opening inthe'base of the discharge section of said chamber. andmeans for operatingsaid conveyor toand fro in said chamber,- said' means being operativelyconnected to one-end thereof remote from; said: discharge openingv wherebysaid other end isfreeto-move into: said discharge opening uporrmovement ofsaid-conveyorin the direction of said: discharge opening.

5. Iniafurnace, the. combination: of achamher having a heating. section, and a discharge sectiom a door normally closing said chamber, aawork holding conveyor having oppositely'disposed. ends. said conveyor being. normally completely contained withinsaid chamber and movableto-and fro betweenthe hea ing section and said discharge section sa d conveyor. being composed. of articulated conveyor elements, a discharge, chute in the base ofv the discha ge section of'said chamber, means for operating said conveyor in either directioninsaid chamber, and guide means for directing one end of sa d conveyor into said discharge chutein one direction of its to-and-fro-motion. '6: In a furnace; the combinationof a'chamber having aheating section and a discharge section, a door normally closing said chamber, a flexible work holdingconveyor having oppositely disposed ends, said conveyor having upturned articulated marginal flanges movable to and fro within saidchamber between said'heating section and normally whol y contained within said heatingsection and'said discharge section, a discharge chute in the base of 'the discharge sectionof said' chamber, and guide means for directing one end'of said conveyor through said discharge chute in one direction of its movement.

7..In a furnace, the combination of a chamber having a heating section and a discharge section, a door, normally closing said chamber, a flexible work holding conveyor within said chamber;

means for-moving'sald conveyorto and fro there'- in between said heating section and said discharge section, a discharge opening in the discharge section of said chamber, and a bridging member movable across said openingto' bridge the same whereby to effect conveyor'movement acrosssaid opening or away from said opening to permit one end of said conveyor to move thereinto, in one direction of its to-and-fro motion in said chamber.

8. Ina furnace, the combination of a chamber having a heating section and a discharge section, a door normally closing said chamber, a flexible-work conveyor normally wholly contained within said heating section; means for moving said conveyor to and fro in said chamber between said heating section and said discharge section, a discharge chute depending from the discharge section of'said chamber, a bridging member solectively movable across the entrance to said discharge chute or inposition to leave said. entrance open, andguide means fordirectingrone-end of: said conveyor into said discharge chutein the latter position ofsaid bridging member.

9. Ina furnace, the combination of a chamberhaving a heating sectionzanda discharge section, a door normally closing said chamber, means for operating said door to open position, a work holding conveyor movable. to and fro in said chamber between the heating section and said discharge section said conveyor having one free end, a dischargechute depending fromthedischarge section of said chambenmeans for operating said conveyor in either direction in said chamber, means for directing the: free. end ofsaid conveyor into said discharge chute, and means for supplying a flow of protective atmosphere in said'chamber and said discharge chute.

10. In a. furnace, thecombination of: a chem.- her having; a. heating section anda discharge section, a door normally closingsaid chamber, means for: operating said door, to open: position, a work. holding. conveyor movable,- to, and; fro insaid chamber 1 between said; heating. section and. said discharge section,- a discharge. opening in the base of the-discharge section. of said chamber, and means controlled in accordance with the, open or closed position of. said door-for directing said conveyor either acrossqorj-intorsaid discharge opening;

1-1. In a furnace, the combination of a. chamher having a heating sectioniand adischarge'section, a discharge chute depending from the discharge section of said chamber, a flexible conveyor having a free end disposed within said chamber, means for operating said conveyor to and fro in said chamber between the heating section and the discharge section, astorage chamber carried by said discharge chute and opening thereinto, and means for directing the free end of said conveyorinto said chute and through said opening in said storage chamber.-

12. In a furnace, thecombination of' a chamber'having aheating section and a discharge-sec tion, a dischargechute depending from the-discharge section of said chamber, a flexible con-- veyor having a free end disposed within said chamber, means for moving-said conveyor to and fro in said chamber between saidheating section and said discharge section, a storage chamber carried by said discharge chute and opening thereinto, means for directing the free end of said conveyor in one direction ofmovement thereof; into-said chute and throughsaid opening in' said storage chamber, and-means for producing a gas 13 flow through said chamber, said chute and said storage chamber.

13. In a furnace, the combination of a chamber having a heating section and a discharge section, a discharge chute depending from said chamber, a flexible conveyor having a free end disposed within said chamber, means for moving said conveyor to and fro between said heating section and said discharge section, an opening in the side of said chute above the lower end thereof and guide means for directing the free end of said conveyor into said chute and through Said opening.

14. In a furnace, the combination of a chamber having a heating section and a discharge section, a discharge chute depending from said chamber, a flexible conveyor having a free end disposed within said chamber, means for moving said conveyor to and fro between said heating section and said discharge section, and spaced guide means in said chute adapted to engage the free end of said conveyor in one direction of movement thereof to direct said end thereof into said chute.

HAROLD J. NESS.

14 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 472,115 Gates et al Apr. 5, 1892 747,887 Igelmann Dec. 22, 1903 964,191 Steele July 12, 1910 1,779,443 Niles Oct. 28, 1930 1,827,413 Ament Oct. 13, 1931 1,899,356 Reis Feb. 28, 1933 1,921,592 Talley Aug. 8, 1933 2,114,182 Guba Apr. 12, 1938 2,114,237 Pink Apr. 12, 1938 2,129,796 Swift Sept. 13, 1938 2,249,219 Nairn et a1 July 15, 1941 2,333,579 Renkin Nov. 2, 1943 2,341,766 Fox Feb. 15, 1944 2,353,948 Swift July 18, 1944 FOREIGN PATENTS Number Country Date 9,817 Great Britain Apr. 26, 1909 

